Treatment of diseases and ailments of the body often benefit from short- or long-term infusion of drugs and/or other fluids. While such medications may be administered extracorporeally, e.g., via transcutaneous injection, many patients benefit from the consistent and repeatable dosage provided by an implanted drug infusion pump. Such pumps may be used in a variety of applications such as control of pain and/or spasticity. They are well-suited to deliver infusate fluids to a targeted delivery site such as an epidural or intrathecal space of the spinal canal, or a particular location within the brain.
Drug infusion pumps are typically implanted subcutaneously, e.g., in the chest or abdominal cavity. The pump may incorporate a chamber to hold the infusate fluid. A needle-penetrable septum may also be provided and is preferably located generally directly beneath the skin. The septum allows drugs or other fluids to be introduced into the infusate chamber by transcutaneous injection. The pump may also include a fluid discharge outlet or stem through which the drug is directed during delivery. The outlet is typically connected to flexible medical tubing, e.g., a catheter, leading to the targeted delivery site.
A secure and leak-free connection of the catheter to the pump outlet is beneficial to ensure correct dosage delivery to the targeted delivery site. If the connection should somehow fail, the intended infusate dosage may not reach the delivery site and, moreover, some (or all) of the infusate could undesirably be dispensed in the vicinity of the pump outlet.
As may be appreciated by those skilled in the art, the connection of the delivery catheter to the discharge outlet may be subjected to various stresses attributable to movement of the patient, as well as to other variables in patient physiology (e.g., weight changes, etc.). These factors may result in separating and/or twisting forces applied at the outlet/catheter connection that, over time, may degrade connection integrity.
Various devices have sought to improve the strength of this connection. For example, raised circular barbs provided on the outlet may resist longitudinal movement of the catheter away from the outlet. In other systems, a suture is provided in place of, or in addition to, the barbs. The sutures may cinch the catheter against the outlet, thereby providing additional resistance to relative catheter motion.
While effective, these catheter connections have drawbacks. For example, barbed stems may not be able to withstand the tensile forces exerted on the catheter due to movements of the patient, or may result in tearing of the catheter in the vicinity of the barb. Moreover, with regard to sutured connections, inherent variability in physician suturing techniques may result in a suture that is incorrectly placed relative to the catheter and connector. As a result, the suture may occlude or otherwise interrupt normal catheter flow. Even when the suture is correctly placed, it may be cinched too tightly—potentially cutting the catheter—or, alternatively, too loosely—potentially reducing the suture's ability to retain the catheter relative to the outlet.